1. Field of the Invention
The present invention relates to contrast media delivery systems. In more particular, the present invention relates to a contrast media delivery system having a flow regulator assembly, diffuser and an improved seat and float assembly which enables the user to simply and efficiently control the flow of contrast media while also minimizing turbulence in a volume of contrast media contained within the system.
2. Relevant Technology
Patient fluid delivery systems have long been used in medicine to ensure safe and reliable delivery of fluids to patients. Typically, such delivery systems include a source of fluid, such as an infusate bag or bottle, a patient access apparatus, such as a catheter or trocar, and delivery tubing for conveying the fluid from the source of fluid to the patient. Some delivery systems also incorporate a burette at one or more positions in the delivery tubing. A burette typically comprises a clear cylindrical apparatus having a chamber of a larger diameter than the delivery tubing. The chamber of the burette is configured to be partially filled with fluid while fluid is flowing to the burette. The chamber of the burette helps eliminate any potential air bubbles in the delivery line. Air bubbles in the delivery line are dissipated as the fluid enters the burette and forms droplets. Additionally, the reservoir of fluid in the burette prevents air from entering into the outlet line of the burette when the flow of fluid from the fluid source to the burette is interrupted.
When the fluid in the fluid source is exhausted, fluid is no longer delivered to the burette from the inlet tubing. Because fluid is no longer delivered to the burette, the fluid level in the burette begins to lower. This allows the practitioner to observe the fluid level in the burette to ascertain whether a replacement fluid source is needed without actually observing the fluid level in the fluid source. As long as the volume of fluid in the burette exceeds a certain threshold, fluid continues to be delivered to the patient from the outlet of the burette. As a result, the burette provides an amount of time in which fluid continues to be delivered to the patient after the fluid source has been depleted. This allows the practitioner to replace the fluid source without interrupting the delivery of fluid to the patient and minimizes the chance for air to be introduced into the fluid path below the burette.
One problem that has been encountered with the use of burettes relates to filling of the chamber of the burette. Typically as the chamber is filled, fluid flowing into the chamber does not immediately contact the volume of fluid in the chamber because the chamber is only partially filled with fluid. Instead, the fluid forms droplets which fall from the burette inlet onto the surface of the fluid volume in the chamber. In some circumstances, when the droplets hit the fluid volume, the velocity of the droplets may create turbulence or microbubbles in the volume of fluid. The formation of microbubbles may be undesirable where the microbubbles may be delivered to the vasculature of the patient.
The formation of microbubbles can be particularly challenging where the fluid being delivered to the patient comprises contrast media. Contrast media is utilized to allow a practitioner to utilize imaging technology such as X-ray or MRI to view the flow of fluids in the patient's vasculature or other body systems. Contrast media typically includes radioactive or isotopic qualities that permit the contrast media to be detected by the imaging equipment. The types of materials that are utilized as contrast media often have a high molecular weight and/or a high viscosity. The high viscosity of contrast media can increase the number and size of microbubbles while also inhibiting the migration of the microbubbles out of the volume of contrast media.
A variety of mechanisms have been developed to minimize the formation of microbubbles in contrast media contained within a burette. One mechanism comprises a ball or other spherical member that is configured to float in the volume of fluid in the burette. The size and buoyancy of the ball is configured such that the droplets strike the surface of the ball instead of the surface of the volume of fluid. This not only slows the velocity of the droplets, but also provides a surface along which the droplets can flow and enter the volume of fluid. Additionally, when the burette is emptied, the ball is configured to provide an air tight seal with the outlet of the burette to prevent air entering the line downstream from the burette when the fluid level reaches the bottom of the burette. By preventing air from entering into the line downstream from the burette, the practitioner does not need to remove air from the line before resuming the flow of fluids to the patient. This allows for smooth and efficient replacement of the fluid source while also resuming the flow of fluid to the patient once the fluid level in the chamber of the burette is returned to normal levels.
One problem that is presented by the configuration of burette float and seat assemblies relates to the air tight seal created between the float and the seat and the related vacuum effect which helps to maintain the air tight seal. The air tight seal and vacuum effect discourages separation of the float from the seat as the drip chamber begins to refill with fluid. Difficulty in separating the float from the seat can occur when the seat is formed from the inner circumference of the chamber. Where the seat is formed from the inner wall of the chamber, the contact between the seat and the float is continuous along much of the bottom surface of the float. As a result, the contact between the seat and the bottom surface of the float can render it difficult for contrast media to flow to the underside of the float. Because buoyancy is created from contact between the contrast media and the underside of the float, insufficient buoyancy is created to overcome the vacuum effect and separation between the float and the seat is inhibited. Additionally, because the contrast media is primarily in contact with the upper surface of the float, downward pressure is exerted on the float by the contrast media. The downward force exerted by the contrast media on the upper surface of the float also prevents separation between the float and the seat.
While the float remains in air tight contact with the seat, flow of contrast media to the patient will not resume. To overcome the vacuum effect and air tight seal between the float and the seat and in attempt to resume the flow of contrast media to the patient, a practitioner may shake or tap the burette in an attempt to dislodge the float. However, shaking or tapping of the burette can result in turbulence in the contrast media and the inadvertent introduction of microbubbles into the contrast media.
Another deficiency of the burette configuration of existing contrast media delivery systems results from the passage of droplets from the inlet of the burette to the volume of contrast media in the burette. In a typical system, when the contrast media enters the burette, it falls from the inlet of the burette until it strikes the surface of the float or the surface of the volume of contrast media. While the float can be configured to be positioned below the inlet of the burette, at least some of the droplets of contrast media can miss the float and directly strike the surface of the volume of contrast media. The falling droplets can result in the formation of turbulence and or microbubbles in the volume of contrast media.